[petsc-dev] PETSc release?

[Kong, Fande]

On Mon, Jul 24, 2017 at 9:36 AM, Jed Brown <jed at jedbrown.org> wrote:

> "Kong, Fande" <fande.kong at inl.gov> writes:
>
> > On Sun, Jul 23, 2017 at 5:31 PM, Jed Brown <jed at jedbrown.org> wrote:
> >
> >> Barry Smith <bsmith at mcs.anl.gov> writes:
> >>
> >> >    Anything stopping us from making a PETSc release?
> >>
> >> I need to finish/test the SF support for MPIUNI that you asked me to do
> >> in June.
> >>
> >> I've also been meaning to add hashtable support for assembly when people
> >> don't preallocate.  I think we should make it automatic.  It isn't much
> >> code and would save the weekly assembly performance emails and would
> >> help a lot for model coupling where our preallocation interfaces (for
> >> off-diagonal blocks) are terrible and the requisite user code is
> >> arguably dirtier than assembly itself.
> >>
> >
> >
> > I am so interested in this.  I am having hard time to make the
> > preallocation right for users because they have all kinds of crazy
> physics
> > that coupling different PDEs together based on their own rules.  So if we
> > could make the preallocate work automatically, it would be great.
> >
> > If we have this code in, the preallocation is not necessary for users any
> > more?  Still worthwhile to  have the right preallocation if possible?
>
> Correct.  The hash needs to be converted to a matrix so the maximum
> memory usage is about double that of precise preallocation in advance.
>


Will  the memory be released in the hash after assembling the matrix?



> But this is only the first assembly, which is usually done before
> setting up preconditioners and Krylov spaces so in most cases would not
> significantly affect the maximum memory usage of the application.
>

If the nonzero structure changes over Newton iterations, and the maximum
memory usage of the application may be larger than that with the precise
preallocation.


Fande,
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